Hello!

I have a 4 axis milling machine (4th axis is rotational) and I would like to know how to make rotational axis to endless rotation (to work as lathe spindle).

Regards

All depends on the setup of your normal spindle but likely the easiest way would be to just set up a new profile for when you want to use it as a lathe.
Hood

No, new profile is not good option, because I need both at the same time. Is it possible to create a profile for lathe (rotational axis is main spinlde) and then use milling spindle as "live tool"? Which M-code starts live tool on lathe?

Another option; is it possible to manually set value of analog output and then write a macro?

Thank you, Denis

No live tooling option in Mach.

Do you have an analogue output? If you have something that can output an analogue signal then a brain or macropump could possibly be used.

Hood

CSMIO/IP-S has two analog outputs.

Ok you should be able to do it via a macro or a brain or whatever you want. I am not sure what the modbus address is for the analogue outs, cant recall seeing it in the manual so you may have to email CS/Lab and ask.
Hood